Advancements in electrorheological fluid: From structural engineering to practical application

An electrorheological (ER) fluid is a smart material with variable structural and rheological properties in response to an electric field. This review reports a comprehensive overview of ER materials and their various microstructures in multi-dimensions (0D, 1D, 2D, and 3D), which are designed to improve yield stress and stability, including hybrid, core-shell, porous, hollow, and anisotropic architectures. Recent advancements in ER materials selection and structural design strategies have been provided to develop high-performance ER fluid, especially in carbon-based ER materials and their nanocomposites. Additionally, several mechanisms of the ER effect were elucidated to provide fundamental insights into the polarization process. Importantly, we showcase the evolution of ER fluids and the ER devices in vibration damping, human-machine interfaces, microfluidics, and soft robotics. These applications drive innovations in next-generation intelligent systems. Finally, we discuss the existing challenges and prospects of ER fluid to highlight trends in ER smart materials.